Help me trouble shoot my Kindle 3

Discussion in 'General Electronics Chat' started by JNBUK, Dec 14, 2012.

  1. JNBUK

    Thread Starter New Member

    Jun 4, 2012
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    I have a 3 year old Amazon Kindle 3 (Now branded as the Kindle Keyboard).

    I had misplaced it during the summer but I found it in an old bag a few days ago, thrilled to have found it again I plugged it in and left it to charge for a day or so.

    Alas, it will not turn on.

    I contacted Amazon about it yesterday and despite it being over 2 years outside warranty they have sent me a brand new one, cant fault that service!

    However, I doubt the issue is a serious one and as they have not requested the old one back I'd like to try and fix it.

    Firstly I have already tried the software resets, they are a no go.

    I have checked the battery voltage, its showing 3.7v despite being on charge for many hours.

    I've checked the power switch and the power delivery, the switch works and the device has power when plugged in.

    Would I be correct in thinking its almost certainly the battery that has died?

    3.7v seems odd given that it has been charging for so long.


    Much obliged!

    James

    Edit:
    I forgot to mention, the device did very briefly turn on at one point but after I put it back to sleep and left it to charge it refused to turn back on.
     
  2. Audioguru

    New Member

    Dec 20, 2007
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    896
    What is the chemistry of the battery and how many cells does it have? Translation, what is the expected voltage of a charged battery?
     
  3. PackratKing

    Well-Known Member

    Jul 13, 2008
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    @ 3.7 volts, if you can identify the + / - on the battery, use a "drain / load " meter to make the batt do some real work.. a hobby motor may draw an amp tops, but will be a cursory indication of battery life. If the motor runs strong, use it to drain the battery down to a point where the motor stops, then charge it overnight a couple cycles...
     
  4. Audioguru

    New Member

    Dec 20, 2007
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    If the battery is multiple cells in series then running it down might cause the weakest cell to be charged in reverse by a stronger cell which might destroy the battery.

    If the battery is Lithium then running it down will destroy it and make it a fire hazzard if a simple charger tries to charge it.
     
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  5. PackratKing

    Well-Known Member

    Jul 13, 2008
    850
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    I don't doubt the veracity of your info, guru, though I must not have gotten that memo... :p

    I routinely run individual lithiums [ power-tool batts ] flat in that manner, in an effort to resurrect them. Some respond, some don't. Never had one overheat.
    I have found a lot of times the factory methods of joining batts on the stainless straps, are often inadequate current carriers, so make for the weak-cell scenario you mention.
    Then, admittedly, the ones that prove worthy, get silver-soldered back into useable packs. Cells that don't take/hold a charge get recycled.
     
  6. Audioguru

    New Member

    Dec 20, 2007
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    The Battery University website assumes that Lithium rechargeable battery cells have a "protection circuit" that disconnects them when the cell voltage drops to 2.2V to 2.9V.
    But I have many lithium battery cells without a protection circuit because it is inside the product. I assume that a lithium battery-powered tool has a protection circuit.

    My radio controlled model airplanes have a protection circuit inside the airplane that disconnects the propulsion motor when the voltage per lithium cell drops below 3.0V but the low current controls still work so I am able to steer and land the airplane. The instructions say to avoid running down to the motor cutoff voltage for longer battery life.
     
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